// /**
//  *
//  * @Author:   tiannanyihao
//  * @Date:     2019-06-20 11:22
//  * @Profile:  rem
//  * @Project:  byf
//
//  * @Description:
//  *
//  */
//
(function (designWidth, maxWidth) {
  var doc = document,
    win = window
  var docEl = doc.documentElement
  var tid
  var rootItem, rootStyle

  function refreshRem () {
    var width = docEl.getBoundingClientRect().width
    if (!maxWidth) {
      maxWidth = 540
    }

    if (width > maxWidth) {
      width = maxWidth
    }
    //与淘宝做法不同，直接采用简单的rem换算方法1rem=100px
    var rem = width * 100 / designWidth
    //兼容UC开始
    rootStyle = 'html{font-size:' + rem + 'px !important}'
    rootItem = document.getElementById('rootsize') || document.createElement('style')
    if (!document.getElementById('rootsize')) {
      document.getElementsByTagName('head')[0].appendChild(rootItem)
      rootItem.id = 'rootsize'
    }
    if (rootItem.styleSheet) {
      rootItem.styleSheet.disabled || (rootItem.styleSheet.cssText = rootStyle)
    } else {
      try {
        rootItem.innerHTML = rootStyle
      } catch (f) {
        rootItem.innerText = rootStyle
      }
    }
    //兼容UC结束
    docEl.style.fontSize = rem + 'px'
  }

  refreshRem()

  win.addEventListener('resize', function () {
    clearTimeout(tid) //防止执行两次
    tid = setTimeout(refreshRem, 300)
  }, false)

  win.addEventListener('pageshow', function (e) {
    if (e.persisted) { // 浏览器后退的时候重新计算
      clearTimeout(tid)
      tid = setTimeout(refreshRem, 300)
    }
  }, false)

  if (doc.readyState === 'complete') {
    doc.body.style.fontSize = '16px'
  } else {
    doc.addEventListener('DOMContentLoaded', function (e) {
      doc.body.style.fontSize = '16px'
    }, false)
  }
})(375, window)



